9,000-mile results are in!
- Thread starter 3 Mad Ponchos
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The oil addition would seem to explain the TBN. The engine uses ~1/2 quart per 1000 miles, but there is no oil added at some of the sampling intervals. Makup oil was added at 8000 miles, but not at 7,000. It would appear that addition of ~1/2 quart of fresh oil with 15 mg KOH equivalents per gram every 1000 miles or so just balances the amount of acid that forms over that interval. So once the TBN reached ~6 mg/gm, it appears to stabilize as the addition of make up oil raises the TBN at the beginning of the next interval. The rate of acid formation in the oil (which is really an oxidation reaction) slows down over time as the more easily oxidizable components in the oil react first. Of course, once the oxidation inhibitors in the additive package become fully depleted, the TBN is going to drop very fast. They you will KNOW the oil is finished.
BTW 3MP, this is a great experiment. I’d like to send you 20 bucks, but I can’t find you on the Cave Drawings link you supplied.
BTW 3MP, this is a great experiment. I’d like to send you 20 bucks, but I can’t find you on the Cave Drawings link you supplied.
I'll be getting my amsoil 5w30 ( in my ls1) tested soon, I have around 10,000 miles on it right now.
2001 Trans am WS6
Alot of city driven.(yorktown, va)
I will also have one done on a 2002 Durango R/T in a few months.
[ May 04, 2003, 06:21 PM: Message edited by: tmgxray ]
Alot of city driven.(yorktown, va)
I will also have one done on a 2002 Durango R/T in a few months.
[ May 04, 2003, 06:21 PM: Message edited by: tmgxray ]
OK guys, you've convinced me to keep it going for now. I asked Blackstone to clarify their analysis recommendations so if they offer contrary advice I will share it. However, the 10k sample will be coming up late this week or early next, so I think we're at least going to 11k.
My little Subaru's 5k oil change is coming up. I'm going to have its oil analyzed as well. The Subaru is about the same age as the Z28 and is running the exact same oil, but it has only 2/3rds the oil capacity and is very heavily weighted to city driving. It should prove an interesting contrast.
Doc, if you go to the Cave Drawings page (http://neptune.spacebears.com/cave/index.html) you'll see an e-mail address going across the page that lights up when you mouse-over. Or you can send a message to the address I use here. But I'm just gonna send you a PM since you're being so nice about it.
Cheers, 3MP
My little Subaru's 5k oil change is coming up. I'm going to have its oil analyzed as well. The Subaru is about the same age as the Z28 and is running the exact same oil, but it has only 2/3rds the oil capacity and is very heavily weighted to city driving. It should prove an interesting contrast.
Doc, if you go to the Cave Drawings page (http://neptune.spacebears.com/cave/index.html) you'll see an e-mail address going across the page that lights up when you mouse-over. Or you can send a message to the address I use here. But I'm just gonna send you a PM since you're being so nice about it.
Cheers, 3MP
Blackstone wrote back and said their main concern at this point is the wear metals.
So guys, how much wear metal is ok?
Cheers, 3MP
So guys, how much wear metal is ok?
Cheers, 3MP
Cummins recommends 100 pmm Fe as the cutoff for OTR diesels. I don't know what the limits are for soft metals like copper. The problem with wear metal accumulation is not abrasion, since normal wear particles are too small to do any serious damage, but additive depletion. After a while, the huge surface area of the accumulated wear particles ties up the detergent/dispersant additives. Metals also act as pro-oxidants since they can act as electron carriers in the complex redox reactions that take place in the oil.
As long as your TBN and particulate levels (indicators of oxidation) hold up, the oil should still be doing a good job.
As long as your TBN and particulate levels (indicators of oxidation) hold up, the oil should still be doing a good job.
Interesting point Drstressor makes about the added oil balancing out the formed acids. So far, 3 quarts of makeup oil have been added--can it be said that this effectively increases the oil capacity by 3 quarts?
3MP, how many quarts did you start out with?
Viscosity looks remarkably stable, and I think you have a long way to go before the oil expires with a TBN of 2!
Jason
3MP, how many quarts did you start out with?
Viscosity looks remarkably stable, and I think you have a long way to go before the oil expires with a TBN of 2!
Jason
Quadrun,
According to some of the research I've seen, adding fresh oil to used oil improves the inhibitors in the short run proportional to the amount of oil added. Since I have a six-quart system, adding half a quart will give it an 8% shot in the arm -- but for how long? My guess is that this half a quart will degrade faster than the initial fill but I haven't run across a detailed analysis of this (yet).
It's something I plan to discuss in depth once the Mobil 1 test is complete, and we know what the final numbers are.
Cheers, 3MP
According to some of the research I've seen, adding fresh oil to used oil improves the inhibitors in the short run proportional to the amount of oil added. Since I have a six-quart system, adding half a quart will give it an 8% shot in the arm -- but for how long? My guess is that this half a quart will degrade faster than the initial fill but I haven't run across a detailed analysis of this (yet).
It's something I plan to discuss in depth once the Mobil 1 test is complete, and we know what the final numbers are.
Cheers, 3MP
MolaKule
Staff member
My personal threshold for irom wear is 40 ppm, after which I dump the oil. Mobil's technical papers seem to think that oil with anything
On the average, however, the trending shows about 4.5 ppm/1k, which is a slightly greater than my comfort zone.
If it were my engine, the oil would get dumped at 10k.
On the average, however, the trending shows about 4.5 ppm/1k, which is a slightly greater than my comfort zone.
If it were my engine, the oil would get dumped at 10k.
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